Prime Minister Benjamin Netanyahu will reach out to the opposition, signaling the Israeli leader’s concern over the two-seat majority government he forged a day earlier under duress.

TEL AVIV—Prime Minister Benjamin Netanyahu will seek to expand his ruling coalition by reaching out to the opposition, a spokesman said Thursday, signaling the Israeli leader’s concern over the two-seat majority government he forged a day earlier under duress.

With just 61 seats of the 120-member parliament, Mr. Netanyahu finds himself at the political mercy of his conservative and religious coalition partners. Despite gaining the...